I am trying to identify an LED driver IC that has had the markings sanded off. It is a L/TQFP-128 package as far as I can tell and from testing with a multimeter each pin is driving a string of 3 or 4 LEDs (depending on colour/forward voltage) and sinking current to turn them on. There are 42 pixels on the PCB with each pixel having 5 different colours for a total of 210 strings of LEDs each IC controlling 105 strings. The single panel has two of these unknown ICs that based on the silkscreen are using a clock, data, latch connection with a series data connection akin to a shift register. I have not had any luck finding any led drivers or shift registers with current control similar to this TB62D612FTG and suspected it may be a microcontroller although assuming each pixel has only one colour active at a time it would still need to be sinking 21 X 20mA (measured) for a total of 420mA which seems far higher than the total current sinking capability of a standard microcontroller.